During the period from 28 December to 16 January the 

 term Q s -Qb is of the order of magnitude of 0.2 gm.-cal./cm. 2 

 per minute. During this same period the Bowen ratio was 

 calculated to have a value close to minus one.* This means 

 that the heat lost by evaporation is nearly balanced by the 

 heat gained through conduction and hence the termed + R) 

 is very small. It is thus seen that the term Q V ~Q ± must ac- 

 count for the excess of incoming radiation, since, as seen 

 from table 3, Q e is equal to 0.028 gm.-cal./cm. per minute 

 and hence is only about 1/7 as large as the termQ s " <?£,. 

 The term q is very difficult to estimate and in most 

 cases in the ocean even impossible. It is generally con- 

 sidered small; however, in the Antarctic Ocean, this assump- 

 tion may not be valid since the shifting of the Antarctic Con- 

 vergence, as described elsewhere in this report, may displace 

 the surface waters by water of very different character. 

 However, since the melting of ice is known to be important 

 during the December-January period, it may be assumed that a 

 considerable portion of the excess radiation goes into melting 

 the ice. 



During the period from 16 January to 3 February, the heat 

 balance is much more difficult to explain. During this period 

 the incoming radiation decreases somewhat and the terms 

 Q-Q b , and Q e (0.195 gm.-cal./cm. 2 per minute) are of the 

 same order of magnitude. Investigation of the Bowen ratio 

 indicates that during this period more heat was lost by evapo- 

 ration than was gained by conduction; in fact, during the last 

 part of the interval, the conduction term also led to a loss of 

 heat from the surface layers. Since the term <?; may be neg- 

 lected during this period, it appears that the advection term, 

 q , must have brought sufficient heat into the area to balance 

 the heat budget. 



These considerations may be applied to a discussion of 



the seasonal change in the thermal structure as indicated by 

 the average curves shown in figure 11. During winter the 

 entire area must be covered by a layer of cold isothermal 

 water. The average curve for late December shows only a 



♦For details on the computation of the term <> 3 -<?* and the 

 Bowen ratio, see SIO Oceanog raphic Report No. 10, 1947. 



21 



